Alloy



Patented Jan. 16, 1940 UNITED STATES PATENT OF-FICE ALLOY Franz It. Hensel and Kenneth L. Emmert, Indianapolis, Ind., assignors to P. R. Mallory & 00., Inc., Indianapolis, Ind.,'a corporation of Delaware .No Drawing. Application June 2, 1939, Serial No. 276,993

Claims. (Cl. 75-173) This invention relates to silver alloys of imwith each other quite readily and by alloying proved physical and electrical characteristics. magnesium with silver, it is possible to increase It is one of the objects of the invention to the solubility of nickel very materially and also provide a silver base material which can be used hold excess nickel in suspension in the silver. for an electrical make and break contact, re- We have found it advisable if we use the larger taining very low contact resistance, having negpercentage of nickel, however, to manufacture ligible material transfer and having great realloys, not by melting, but by sintering together sistance to welding and sticking under severe the ingredients. By using the sintering method, electrical loads. which fundamentally consists in mixing the met- 10 Another object of the invention is to provide a1 powders, pressing and sintering with or witha new silver base alloy which has increased tenout additional re-sintering and re-pressing opsile strength and which can be cold worked seerations, we can incorporate nickel contents as verely and retain a high annealing point, after high as to Alloys of such high nickel such cold working. content have the advantage that for applications It is a further object to provide a material such as electrical contacts, characteristics are which shows considerable improvements, as far obtained which provide a material that will not as corrosion resistance is concerned. fuse together readily and that will show very Other objects of the invention will be apparent small transfer.

from the following description, taken in connec- If thealloys are to be used for chemical purtion with the appended claims. poses, of other applications where a melted The present invention comprises a combinaproduct is desired, the amount of nickel that is tion of elements, methods of manufacture, and most desirable, ranges from about 0.25 to 5%. the products thereof, brought out and exempli- We have found in our studies that even with a fled in the disclosure hereinafter set forth, the small nickel content the annealing temperatures 80098 t e ve t being dicated in the of cold worked material are raised by several appended claims, I hundred degrees Fahrenheit.

While a preferred embodim f the inven- We have investigated a series of compositions, tion is described herein, it is contemplated that and we have found that the following ranges,

considerable variation may be made in the methwhich are given by way f example, have shown 0d of procedure and the combination of elevery excellent physical properties:

ments, without departing from the spirit of the Per cent invention (1) Magnesium 1 4 The present invention contemplates an allo Nickel 351205 of silver with magnesium and nickel. 1n the silver Balance 8 formation of the new alloy, it is preferable to (2) Magnesium ztoa provide a composition of the materials specified Nickel .25 to 5 in the following proportions: Silver Balance Per (3) Magnesium 1 an Magnesium to Nickel 2 5 -Nickel .1 to 40 silver Balance Silver Substantially the balance (4) Magnesium 1 to 8 The preferred range of magnesium is .05 to 8%, Nickel 15 to) because, up to that percentage, magnesium is Silver Balance taken up in alpha solution in silver and we have (5) Magnesium 5 to 15 found that silver and magnesium up to 8% can Nickel .25 02.5 be alloyed very readily, and the cast ingots can silver be rolled, swaged or drawn in the desirable (5) Magnesium 15 Nickel 2.5 to 30 shapes, such as sheet, bar stock, wire, strips or the like. The range of magnesium from 1 to 4% silver i is especially useful. The tensile strength of the improved alloys Silver and nickel are mutually soluble only to is materially increased by the combined addition a very limited extent, the solid solubility being of magnesium and nickel, without any ppreonly approximately 0.25% of nickel in silver. ciable loss of ductility. It is possible to obtain However, magnesium and nickel form alloys a Brinell hardness of to 0., by proper cold working. With a sufficiently high magnesium content, tensile strength values in the neighborhood of 50,000 pounds per square inch can even be obtained in the annealed condition.

The present alloy has outstanding merit if used for electrical purposes. In a comparison test, wherein contacts of similar dimensions were used on a resistive inductive circuit at 470 cycles per minute and wherein the current flowing in the circuit was increased periodically, to obtain the definite current values of the alloys of the nature described above, in comparison with contact materials produced in the prior art, it was found that both the material transfer and the contact resistance showed an improvement over the alloys of the prior art.

The alloys of the present invention have been found useful for a large number of electrical contact applications, such as for instance, sensitive direct current relays, over-load cut outs, voltage regulators, indicating and recording gaugers, thermostatic controls and the like. 1

The other uses of the alloy are in the form of silverware, particularly such silverware as is used for industrial applications, and where good corrosion resistance, high tensile strength and high annealing temperatures are required. Alloys may also be used for jewelry purposes and tableware.

Materials of the type described with a higher nickel content, can also be used for electrical brushes and arcing tips. It has been found advantageous to incorporate such materials as graphite into the mixture. It is also possible to incorporate conductive oxides into the composition covered by the present invention. If, for certain applications, the material must retain a certain porosity, then a sintering process should be used which will provide a material with about 15 to 30% of voids. These voids can be later on filled with special oils or greases, in order to provide improved lubricating characteristics.

The alloy of the present invention has a commercial advantage, since the addition of magnesium in the percentage contemplated provides a material of lower specific gravity than the materials of the present art, and therefore it is possible to produce a larger number of finished products per unit weight of material.

While the present invention as to its objects and advantages has been described herein as carried out in specific embodiments thereof, it is not desired 'to be limited thereby, but it is intended to cover the invention broadly; within the spirit and scope of the appended claims.

What is claimed is: 1..An alloy composed of .05 to 8% magnesium, .25 to 5% nickel, balance substantially all silver. 2. An alloy composed of 1 to 4% magnesium, .25 to 5% nickel, balance substantially all silver. 3. An alloy composed of 2 to 8% magnesium, .25 to 5% nickel, balance substantially all silver. 4. An alloy composed of 5 to 15% magnesium, .25 to 2.5% nickel, balance substantially all silver. 5. An alloy composed of .05 to 15% magnesium, .25 to 5% nickel, balance substantially all silver.

FRANZ R. HEN SEL. KENNETH L. EMMERT. 

